1. Field of the Invention
The invention relates to control circuits for producing analog output control voltages which may be varied in accordance with digital input signals to control a process, device, etc.
2. Description of the Prior Art
The prior art, as exemplified in U.S. Pat. Nos. 3,059,223, No. 3,247,507, No. 3,249,769, No. 3,317,828, No. 3,496,562, No. 3,505,531, No. 3,513,468, No. 3,548,169, No. 3,579,146, and No. 3,757,131, contains a number of circuits including process controlling digital-to-analog circuits, and standby power circuits for memories or counters. Prior art devices and systems for generating analog control signals in accordance with digital input signals, such as from a computer, often used mechanical devices such as stepping motors pulsed incrementally to control an analog output voltage; such controlling device requiring separate circuitry to respond to analog input control voltage or types of input signals. Additionally, prior art circuits generally had many deficiencies such as being excessively expensive, unreliable or being incapable of being readily adapted to respond to a number of input signals such as pulse incremental signals, pulse duration signals, or analog input signals.